Dynamic seal for molding process and method of using

ABSTRACT

The invention relates to a dynamic mold seal for use in a method of molding apparatus to mold a polymeric frame or gasket onto the periphery of a glass sheet. The seal and method are preferably utilized to form a vehicle window.

BACKGROUND OF INVENTION

The invention relates to a mold seal which allows an improved method ofmolding a polymeric material onto at least a portion of the periphery ofa sheet of substrate material. More particularly, the invention relatesto utilizing the subject seal in a molding apparatus to mold a polymericframe or gasket onto the periphery of a glass window for a vehicle.

It is known to mold an elastomeric gasket or frame member onto theperiphery of a substrate such as glass to form products such as vehiclewindows. Common molding methods are reaction injection molding (RIM) andinjection molding. Such molded-on members have become increasinglycomplex and, as a result, the molding apparatus used in making suchmolded-on members have likewise become more complex.

To create the profiles desired in such elastomeric members, it issometimes necessary to manage the flow of the polymeric molding materialwithin the molding apparatus. Among the methods utilized for suchmanagement of liquid polymeric molding material are so-called “softseals.” In typical known soft seals, it is often necessary to have asoft seal in opposing relationship on each major surface of thesubstrate onto which the gasket is to be molded. Such sealconfigurations generally do not permit molding up to the edge of themajor surface of the substrate, which can be a detriment, bothaesthetically and functionally. Therefore, it would be desirable to havea method of molding requiring a single soft seal that would permitcomplex molded profiles extending to, and even beyond the edge of amajor surface of the substrate.

SUMMARY OF THE INVENTION

The invention relates to a mold seal which allows, in a simple andcost-effective manner, an improved method of molding a polymericmaterial onto at least a portion of the periphery of a sheet ofsubstrate material. More particularly, the invention relates toutilizing the subject seal in a molding apparatus to mold a polymericframe or gasket onto the periphery of a glass window for a vehicle.Still more particularly, the invention relates to a dynamic mold sealwhich, working in cooperation with at least one movable mold portion,permits molding up to the edge of a major surface of a sheet ofsubstrate material, or even beyond the edge of a major surface of asheet of substrate material if desired.

The dynamic mold seal of the invention includes a base portion, anintermediate portion, a straight arm portion and a flexible arm portion.Preferably, the subject mold seal is an integral assembly including thepreviously mentioned elements. In any desired configuration, theintermediate portion extends from the base portion, and the straight andflexible arm portions extend from the intermediate portion, but indifferent directions from one another. The flexible arm is capable ofmovement due to the presence of an “elbow,” allowing the flexible arm tomove into and out of sealing contact with at least a portion of aperipheral edge of the sheet of substrate material. At the same time,the straight arm portion is adapted to sealingly engage at least aportion of a major surface of the substrate material.

The invention also relates in another aspect to the utilization of thepreviously described dynamic mold seal in a molding apparatus to form anencapsulated substrate, such as a vehicle window having a molded-onframe or gasket.

The molding apparatus in which the dynamic seal is utilized includesupper and lower mold halves, either or both of which may have a moldcavity formed therein. In a mold half containing a mold cavity, a sealcavity will also be formed to receive the base portion of the dynamicseal of the invention. At least one movable mold portion is alsoincluded in the mold half having the seal cavity. The at least onemovable mold portion is located so that the flexible arm portion of thedynamic seal is within the range of movement of the movable moldportion.

In preparing to conduct a molding operation, the dynamic seal of theinvention will have been affixed in the cavity seal. A sheet ofsubstrate material, for example a glass vehicle window, will be placedin the mold cavity such that at least a portion of the peripheral edgeof the vehicle window is proximate the dynamic seal of the invention.The straight arm portion of the seal is in sealing contact with a majorsurface of the vehicle window; that is, the inner major surface of thevehicle window. Closure of the mold halves actuates the movable moldportion, causing it to come into pressing contact with the flexible armof the seal of the invention. The flexible arm is deflected toward, andinto sealing contact with, at least a portion of the peripheral edge ofthe vehicle window. Then, liquid polymeric material is injected into themolding apparatus to fill the mold cavity. Due to the action of the sealof the invention, such liquid polymeric material is prevented fromcoming into molding contact with either of at least a portion of theperipheral edge of the vehicle window or a portion of the inner majorsurface of the vehicle window. A polymeric frame or gasket is formed,however, around the remaining portion of the periphery of the vehiclewindow.

The liquid polymeric material is allowed to cure in the mold cavity andthus bond to the at least a portion of the periphery of the vehiclewindow. Once sufficient curing has occurred, the mold halves are opened,and the movable portion of the mold retracts from its extended position,releasing the pressure exerted on the flexible arm of the subject seal.The flexible arm of the seal moves away from the periphery of thenow-encapsulated vehicle window, which can be removed from the moldcavity.

BRIEF DESCRIPTION OF THE DRAWINGS

The advantages described herein, as well as other advantages of thepresent invention, will become readily apparent to those skilled in theart from the following detailed description of the preferred embodimentwhen considered in light of the accompanying drawings.

FIG. 1 is a perspective view of a lower mold half of the moldingapparatus according to the invention.

FIG. 2 is a cross-sectional view of the upper and lower mold halves inmolding contact and containing the subject dynamic seal according to theinvention.

FIG. 3 is a cross-sectional detailed view of the molding apparatusaccording to the invention, particularly illustrating the movable moldportion interacting with the dynamic seal.

FIG. 4 a-c are cross-sectional views of the profiles of representativeframes or gaskets which can be molded utilizing the seal and method ofthe present invention.

FIG. 5 is a cross-sectional view of a molding apparatus containing asoft seal typical of those known from the patent literature.

DETAILED DESCRIPTION OF THE INVENTION

Molding of an elastomeric frame or gasket onto the periphery of, forexample, a vehicle window to form a so-called modular window assembly,which can then be conveniently installed in an opening in a vehiclebody, is well known. Even so, placing a piece of glass into an injectionmolding apparatus and subjecting it to several thousand pounds persquare inch of molding pressure in order to mold on the peripherythereof a polymeric frame or gasket without breaking the glass whileobtaining a strong bond between glass and the polymeric frame or gasket,presents a number of technological challenges.

As previously noted, highly complex molding apparatus to create complexmolding profiles have been proposed. Typically, such apparatus have oneor more means of directing the liquid polymeric molding material to aparticular area of the mold, or conversely, preventing the flow of thepolymeric material into a particular portion of the mold. As previouslynoted, movable mold portions and so-called “soft seals” are among thesemeans. An example of a typical known soft seal is illustrated in FIG. 5.The typical, previously known soft seal illustrated in FIG. 5 requiresopposing seals 60 and 62. The soft seals shown in FIG. 5 do not allowmolding up to or even over the edge of a vehicle window during a moldingoperation. Also, while typical soft seals allow for some variation inglass dimensions and configuration, they are, generally, quite limitedin this regard. Typical soft seals are also susceptible to beingdislodged from their position in the mold by the pressures in the moldcreated by the molding operation. This is particularly, an issue withinjection molding processes.

The mold seal of the invention, by contrast, is relatively simple inthat only a single seal is necessary, rather the two or more as shown inFIG. 5 herein, while allowing molding up to and beyond the peripheraledge of the glass sheet, as well as accommodating significant variationsin glass size and shape during the molding process. Further, thecooperation between a movable mold portion and the present mold seal notonly causes the effective functioning of the mold seal, by allowing itto move into and out of sealing engagement with the substrate, but themovable mold portion assists in preventing the mold seal from beingdislodged from the mold cavity during the molding operation.

FIG. 1 shows a mold half 10 of the invention having a mold cavity 12which will receive the liquid polymeric molding material. One or moremeans of conveying the polymeric material (not shown) into the moldcavity 12 will be present, e.g. one or more sprues and a cold/hot runnersystem, but are well known and not part of the invention. When placedinto the mold half 10, the glass sheet 14 will be supported by one ormore resilient support members 16 proximate seal cavity 18 and withinthe range of movement of movable mold portion 20. As will be describedin more detail, the base of mold seal 22 is configured to be insertableinto seal cavity 18. Lower mold half 10 can be made of steel, aluminumor other suitable material.

FIG. 2 is a cross-sectional view of the lower mold half 10 of FIG. 1 inintimate molding contact with upper mold half 24. A glass sheet 14 is inthe closed molding apparatus ready for the molding operation to occur.Similar to lower mold half 10, upper mold half 24 may be made fromaluminum, steel or other suitable material.

FIG. 3 shows the mold seal 22 of the invention as shown, generally, inFIG. 2 in greater detail. As can be seen, the mold seal 22 of theinvention is comprised of a base portion 26 configured to be insertedinto seal cavity 18, an intermediate seal portion 28 which connects thebase portion 26 of the seal with the flexible arm 30, and straight arm32. Mold seal 22 can be made from any suitable resilient polymericmaterial, for example, EPDM, silicone and thermoplastic elastomers(TPE), as well as combinations thereof.

Flexible arm 30 and straight arm 32 extend from the intermediate sealportion 28 in different directions from one another, such that straightarm 32 sealingly contacts a major surface 34 of glass sheet 14. Bycontrast, flexible arm 30, made “flexible” by virtue of an elbowportion, for example, a cut-out 36 or other suitable means, ispositioned proximate peripheral edge 38 of glass sheet 14. Undernon-molding conditions, flexible arm 30 is not in contact withperipheral edge 38. During molding operations, movable mold portion 20will urge flexible arm 30 into sealing contact with peripheral edge 38as illustrated in FIGS. 2 and 3, the direction of movement of themovable mold portion 20 being particularly shown by the arrow. Flexiblearm 30 is capable of movement of on the order of 10°-15°. The point atwhich flexible arm 30 contacts peripheral edge 38 can be adjusted so asto allow the liquid polymeric molding material to bond to varyingproportions of the peripheral edge of the glass sheet so as to formdifferent molding profiles, as illustrated in FIG. 4. Movable moldportion 20 is activated upon the closing of upper and lower mold halves24 and 10. After completion of a molding cycle, the mold halves 24 and10 are opened, the movable mold portion retracts, thus allowing flexiblearm 30 to once again move out of molding contact with peripheral edge38.

It is within the scope of the invention for mold seal 22, seal cavity 18and movable mold portion 20 to be present only in selected portions ofthe periphery of glass sheet 14, as well as to be present around thecomplete periphery of glass sheet 14 as shown in FIG. 1.

FIG. 4 illustrates some of the versatility of mold seal 22. FIG. 4 ashows the capability of molding up to the transition between majorsurface 40 and peripheral edge 38 of glass sheet 14. FIG. 4 b shows how,with adjustment of the position of mold seal 22, molding past thetransition point between major surface 40 and peripheral edge 38 to anintermediate position on the edge of the glass sheet can beaccomplished. Finally, FIG. 4 c shows how the mold seal 22 of thepresent invention can be utilized to mold a polymeric frame, gasket orthe like to form a so-called two-side encapsulation; i.e., a peripheralportion of a major surface and a peripheral edge of a glass sheet.

In accordance with the provisions of the patent statutes, the principlesand mode of operation of the present invention have been described inwhat is considered to represent the preferred embodiment. It should beunderstood, however, that the invention may be practiced otherwise thanas specifically illustrated and described without departing from thescope of the claims herein.

1. A molding apparatus comprising: upper and lower mold halves, at leastone of the upper and lower mold halves having a molding cavity, a sealcavity and at least one movable mold portion formed therein; and adynamic seal comprising a base portion, an intermediate seal portion, astraight arm portion and a flexible arm portion, each arm portionextending from the intermediate seal portion, the base portion beingpositioned within at least a portion of the seal cavity; wherein when asheet of a substrate material is placed between the upper and lower moldhalves, at least a portion of the periphery of the sheet is within themolding cavity proximate the dynamic seal, such that the straight armportion is in sealing contact with a major surface of the sheet, and theflexible arm is proximate at least a portion of the peripheral edge ofthe sheet of substrate material, and whereby closing the upper and lowermold halves causes the at least one moveable mold portion to contact theflexible arm and sealingly press the flexible arm against the peripheraledge of the sheet.
 2. The molding apparatus defined in claim 1, whereinthe seal comprises an integral elbow portion connecting the flexible armto the intermediate seal portion so as to allow movement of the flexiblearm.
 3. The dynamic seal defined in claim 2, wherein the elbow portionis formed by a cut-out in the flexible arm.
 4. The molding apparatusdefined in claim 1, wherein the seal is comprised of an ethylenepropylene diene M-class rubber material.
 5. The dynamic seal defined inclaim 1, wherein the seal is comprised of a silicone material.
 6. Thedynamic seal defined in claim 1, wherein the flexible arm portion iscapable of moving in an arc of at least 10°.
 7. The dynamic seal definedin claim 6, wherein the flexible arm portion is capable of moving in anarc of 10-15°.
 8. A method of making a molding utilizing a dynamic sealin a molding apparatus comprising: providing a molding apparatuscomprising upper and lower mold halves, at least one of the upper andlower mold halves having a molding cavity, a seal cavity and at leastone movable mold portion formed therein; providing a preformed, integraldynamic seal comprising a base portion, an intermediate seal portion, astraight arm portion and a flexible arm portion, each arm portionextending from the intermediate seal portion, but in differentdirections; placing the base portion of the dynamic seal into at least aportion of the seal cavity in a manner so as to prevent its movementwithin, or its removal from, the seal cavity, and allowing theintermediate seal portion and arm portions to extend out of the sealcavity into the molding cavity; placing a sheet of a substrate materialinto the molding cavity, at least a portion of the peripheral portion ofthe substrate being proximate the dynamic seal, such that the straightarm portion is in sealing contact with a major surface of the sheet ofsubstrate material, and the flexible arm is proximate at least a portionof the peripheral edge of the sheet of substrate material; closing theupper and lower mold halves, which action causes the at least onemoveable mold portion to contact the flexible arm and sealingly pressesthe flexible arm against the peripheral edge of the sheet of substratematerial; injecting a liquid polymeric material into the mold cavitywhere it is allowed to flow at least up to the edge of the peripheraledge of the sheet of substrate material, but is prevented from flowingpast where the flexible arm is in sealing contact with the peripheraledge of the sheet of substrate material; allowing a sufficient time forthe polymeric material to cure; opening the mold halves, thusdisengaging the movable mold portion from sealing contact with theflexible arm of the dynamic seal, and allowing the flexible arm to moveout of sealing contact with the portion of the peripheral edge of thesubstrate material; and removing the substrate with polymeric materialmolded thereon from the molding apparatus.
 9. The method defined inclaim 8, wherein the polymeric molding material is a thermoplasticmaterial.
 10. The method defined in claim 9, wherein the polymericmolding material is comprised of polyvinylchloride.
 11. The methoddefined in claim 8, wherein the molding pressure is ≧2000 psi.
 12. Themethod defined in claim 8, wherein the liquid polymeric material isallowed to flow past where the outer major surface of the substratematerial ends and the peripheral edge portion of the substrate materialbegins.